宁南山区人工林草对土壤真菌群落的影响

以宁南山区天然草地（长芒草（Stipa bungeana Trin））为参照，选取2种典型人工恢复植被：人工草地（苜蓿（Medicago sativa））和人工林地（柠条（Caragana korshinskii Kom））的表层土壤（0-20cm）为研究对象，利用Miseq高通量测序技术分析土壤真菌的多样性、物种组成及其相对丰度变化特征，并采用冗余分析（RDA）的方法研究环境因子对不同植被土壤真菌群落的影响.结果表明：3种植被样地土壤样品共测得真菌27个门，44个纲，70个目，91个科.其中，优势菌门有子囊菌门（Ascomycota）和担子菌门（Basidiomycota），丰度分别为71.8%和15.2%；优势菌纲主要有：粪壳菌纲（Sordariomycetes）、座囊菌纲（Dothideomycetes）、伞菌纲（Agaricomycetes）和盘菌纲（Pezizomycetes）；优势菌属有：赤霉菌属（Gibberella）、肾形虫属（Colpoda）、水球壳属（Hydropisphaera）、叶生壳属（Floricola）、管柄囊霉属（Funneliformis）和Marcelleina.土壤真菌丰富度和多样性在苜蓿地最大，柠条地最小.球囊菌门（Glomeromycota）在天然草地的丰度最高，为4.8%；子囊菌门丰度在苜蓿地里最大，达82.6%，在柠条地最低，为56.8%；担子菌门和分类不明确门（Unclassified）在柠条土壤中丰度最大，分别为：25.3%和7.9%，在苜蓿地中最低，分别为：7.1%和0.8%.盘菌纲在天然草地中的丰度最高，为17.8%，且显著高于柠条地.伞菌纲在（Agaricomycetes）柠条地中的丰度明显高于苜蓿地.Heatmap热图分析表明，尽管苜蓿地中土壤真菌群落与天然草地的相似度更高，但是天然草地中AM真菌（Arbuscular mycorrhizal Fungi）的相对丰度最大，种植苜蓿使土壤致病菌属的相对丰度增加，柠条地的肾形虫属相对丰度最高.人工林草对土壤真菌的群落组成和多样性有较明显的影响.土壤水分（SW）、有机碳（TOC）和全氮（TN）是影响宁南山区林草地土壤真菌群落的主要理化因子.

Effects of artificial forest and grass on soil fungal community at southern Ningxia mountain

It is of importance to evaluate potential ofsoil fertility and health status after vegetation restoration at southern Ningxia mountain, Chinese Loess Plateau. Therefore, three typical grasslands, including the Stipa bungeana Trin (SB) of natural grassland restoration, the Medicago sativa (MS) of artificial grassland reatoration and Caragana korshinskii Kom (CK) of artificial shrub restoration were selected as experimental sites. Fungi community composition and diversity of surface soil (0~20cm) were analyzed by using Miseq high-throughput sequencing technology. Response of soil fungi communities to environmental factors was assessed through redundancyanalysis (RDA). The identified taxa in various resolutions were:27 phyla, 44 classes, 70 orders and 91 families. The dominant phyla were Ascomycota and Basidiomycota, with relative abundance of 71.8% and15.2%, respectively. The dominant classes were Sordariomycetes, Dothideomycetes, Agaricomycetes and Pezizomycetes. Gibberella, Colpoda, Hydropisphaera, Floricola, Funneliformis and Marcelleina were the dominant genera in this study. Abundance and diversity of soil fungi were highest in MS and lowest in CK. Abundance of Glomeromycota were were highest in SB (4.8%); abundance of Ascomycota were highest in MS (82.6%) lowest in CK (56.8%); abundance of Basidiomycota and Unclassified were highest in MS (25.3% and 7.9%, respectively) and lowest in MS (7.1% and 0.8%, respectively). Abundance of Pezizomycetes were highest in SB (17.8%) and had significant difference correlated to CK. Atthe site of SB, abundance of Agaricomycetes were highest and obviously higher than that of CK. Heatmap shows that although there were similarities of soil fungi communities between MS and SB. SB, MS and CK had the highest abundance of Arbuscular mycorrhizal fungi, soil pathogenic fungi and Colpoda (a kind of protozoan), respectively. In conclusion, compared to the restoration of natural grassland, restoration of artificial grassland and shrub had great influence on the community composition and diversity of soil fungi. RDA showed that soil water, total organic carbon and total nitrogen were the main soil parameters influencing fungal communities.